How do you find the dimensions to make a perfect sized print for a brick?

[Sami2ss]

Something I don't understand for some print bricks is how people find the perfect dimensions to keep their print from stretching on peculiar print bricks, like the picture frame in the decoration brick pack.

[Ad Bot]

[KoopaScooper]

open the zip containing files
look at files resolutions
????
profit

[KoopaScooper]

forget i didn't read
it uses 2x2f and it says it on the description
but the ratio is 3:4 if you care